New to 13 (we are using 13.0.476 Fall quarter)

This is not meant to be an exhaustive list, but
important new features of 13.
For a more information on 13 see also what's new in 13.0.237.

use of alt or space for moving in the
viewport window

Experimental OpenCL - smoke and
pyro solvers use OpenCL for extra speed when available.
Advantage is to use all RAM on the system (GPU is limited to
RAM on the video card).

What is OpenCL? - Open Computing Language - a framework for
writing programs that execute in parallel across CPUs (central
processing units), GPUs (graphics processing units), DSPs (digital
signal processors) and FPGAs (field-programmable gate arrays).
OpenCL is by a non-profit technology consortium Khronos Group,
initially developed by Apple. OpenCL can be used to give an
application graphics processing unit power for non-graphical
computing. OpenCL consists of a set of headers and a shared
object. An installable client driver loader (ICD loader) must be
installed on the OS for it to work. (taken from wiki).

Not only is Houdini using linear work space (gamma
2.2) by default - the vex texture functions that work on
8-bit images will convert from sRGB to linear (and have a
srccolorspace variadic argument to specify the color space).

under the geometry container render tab you can display
low-detail proxies of geometry using the "Display as"
options of points, bounding box or centroid

vex and vop networks can now create geometry! in the
attrib wrangle sop, attrib vop sop and volume vop sop, and
geometry vop dop using the new addpoint, addprim and addvertex
functions. Other features are new
as well